﻿using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Data.SQLite;
using System.Linq;
using System.Text;

namespace laicigoujiaoyi
{

        /// <summary> 
        /// 说明：这是一个针对System.Data.SQLite的数据库常规操作封装的通用类。 
        /// </summary> 
        public class SQLiteDBHelper
        {
            private string connectionString = string.Empty;
            /// <summary> 
            /// 构造函数 
            /// </summary> 
            /// <param name="dbPath">SQLite数据库文件路径</param> 
            public SQLiteDBHelper(string dbPath)
            {
                this.connectionString = "Data Source =" + dbPath;
            }
            /// <summary> 
            /// 创建SQLite数据库文件 
            /// </summary> 
            /// <param name="dbPath">要创建的SQLite数据库文件路径</param> 
            public static void CreateDB(string dbPath)
            {
                using (SQLiteConnection connection = new SQLiteConnection("Data Source=" + dbPath))
                {
                    connection.Open();
                    using (SQLiteCommand command = new SQLiteCommand(connection))
                    {
                        command.CommandText = "CREATE TABLE Demo(id integer NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE)";
                        command.ExecuteNonQuery();
                        command.CommandText = "DROP TABLE Demo";
                        command.ExecuteNonQuery();
                    }
                }
            }
            /// <summary> 
            /// 对SQLite数据库执行增删改操作，返回受影响的行数。 
            /// </summary> 
            /// <param name="sql">要执行的增删改的SQL语句</param> 
            /// <param name="parameters">执行增删改语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param> 
            /// <returns></returns> 
            public int ExecuteNonQuery(string sql, SQLiteParameter[] parameters)
            {
                int affectedRows = 0;
                using (SQLiteConnection connection = new SQLiteConnection(connectionString))
                {
                    connection.Open();
                    using (DbTransaction transaction = connection.BeginTransaction())
                    {
                        using (SQLiteCommand command = new SQLiteCommand(connection))
                        {
                            command.CommandText = sql;
                            if (parameters != null)
                            {
                                command.Parameters.AddRange(parameters);
                            }
                            affectedRows = command.ExecuteNonQuery();
                        }
                        transaction.Commit();
                    }
                }
                return affectedRows;
            }
            /// <summary> 
            /// 执行一个查询语句，返回一个关联的SQLiteDataReader实例 
            /// </summary> 
            /// <param name="sql">要执行的查询语句</param> 
            /// <param name="parameters">执行SQL查询语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param> 
            /// <returns></returns> 
            public SQLiteDataReader ExecuteReader(string sql, SQLiteParameter[] parameters)
            {
                SQLiteConnection connection = new SQLiteConnection(connectionString);
                SQLiteCommand command = new SQLiteCommand(sql, connection);
                if (parameters != null)
                {
                    command.Parameters.AddRange(parameters);
                }
                connection.Open();
                return command.ExecuteReader(CommandBehavior.CloseConnection);
            }
            /// <summary> 
            /// 执行一个查询语句，返回一个包含查询结果的DataTable 
            /// </summary> 
            /// <param name="sql">要执行的查询语句</param> 
            /// <param name="parameters">执行SQL查询语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param> 
            /// <returns></returns> 
            public DataTable ExecuteDataTable(string sql, SQLiteParameter[] parameters)
            {
                using (SQLiteConnection connection = new SQLiteConnection(connectionString))
                {
                    using (SQLiteCommand command = new SQLiteCommand(sql, connection))
                    {
                        if (parameters != null)
                        {
                            command.Parameters.AddRange(parameters);
                        }
                        SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
                        DataTable data = new DataTable();
                       adapter.Fill(data);
                        return data;
                    }
                }
            }
            /// <summary> 
            /// 执行一个查询语句，返回查询结果的第一行第一列 
            /// </summary> 
            /// <param name="sql">要执行的查询语句</param> 
            /// <param name="parameters">执行SQL查询语句所需要的参数，参数必须以它们在SQL语句中的顺序为准</param> 
            /// <returns></returns> 
            public Object ExecuteScalar(string sql, SQLiteParameter[] parameters)
            {
                using (SQLiteConnection connection = new SQLiteConnection(connectionString))
                {
                    using (SQLiteCommand command = new SQLiteCommand(sql, connection))
                    {
                        if (parameters != null)
                        {
                            command.Parameters.AddRange(parameters);
                        }
                        SQLiteDataAdapter adapter = new SQLiteDataAdapter(command);
                        DataTable data = new DataTable();
                        adapter.Fill(data);
                        return data;
                    }
                }
            }
            /// <summary> 
            /// 查询数据库中的所有数据类型信息 
            /// </summary> 
            /// <returns></returns> 
            public DataTable GetSchema()
            {
                using (SQLiteConnection connection = new SQLiteConnection(connectionString))
                {
                    connection.Open();
                    DataTable data = connection.GetSchema("TABLES");
                    connection.Close();
                    //foreach (DataColumn column in data.Columns) 
                    //{ 
                    //  Console.WriteLine(column.ColumnName); 
                    //} 
                    return data;
                }
            }


        }
    
}

